It is desirable for a number of reasons to cause material to flow in non-ferrous molten metal furnaces. Magnetic pumps are sometimes used to induce eddy currents in the metal in order to induce such flow or agitation. Electromagnetic devices are used in some known pumps, and permanent magnets are used in other such pumps. Such pumps are typically attached to the outside of a side wall of a furnace, and the molten metal may be piped into and around the pump structure (as in published U.S. patent application publication numbers 2011/0248432 and 2010/0244338, which are both incorporated herein by reference). This means that molten metal is moved outside the furnace, elevating the likelihood of an uncontained leak from such pumps and associated structures. Moreover, some existing devices project magnetic flux through furnace external walls, which need to be thick for safety reasons.
Each of these approaches can be inefficient in agitating molten metal and create a significant risk of leakage of molten metal through the side wall of the furnace or within the structures outside the furnace and through which the metal flows. Such a leak or breach may result in significant risk of leakage outside the pump structure, not to mention the risk of damage to the pump structure.